Alright, let's work through 3543 times 5815 step by step
3543 × 5815 = 5815 × (3543)
+ 5815 × 3 which equals 17445
+ 5815 × 40 resulting in 232600
+ 5815 × 500 that is equal 2907500
+ 5815 × 3000 that results in 17445000

= 20602545
